Tree to Tree

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singular experience of designing and

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The tree canopy walk, designed by Metcalfe Architecture & Design

the 2010 AIA Philadelphia Awards for Design Excellence Gold Medal and the American Association of Museums 2010 Excellence in Exhibition Design Award.

The Design of a Tree Canopy Walk

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METCALFE ARCHITECTURE & DESIGN

MORRIS ARBORETUM OF THE UNIVERSITY OF PENNSYLVANIA

215.557.9200

Metcalfe Architecture & Design of Philadelphia,

University of Pennsylvania, a 92-acre pleasure

by at the

www.metarchdesign.com

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tree to tree for the Morris Arboretum of the University of Pennsylvania, won

the sky. The award-winning exhibit, designed by

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Commonwealth of Pennsylvania.

tree to tree

The Design of a Tree Canopy Walk

BY METCALFE ARCHITECTURE & DESIGN AT THE MORRIS ARBORETUM OF THE UNIVERSITY OF PENNSYLVANIA

Tree to Tree

The Design of a Tree Canopy Walk DESIGNED BY METCALFE ARCHITECTURE & DESIGN PHILADELPHIA , PA FOR THE MORRIS ARBORETUM OF THE UNIVERSITY OF PENNSYLVANIA

COPYRIGHT

© 2011

METCALFE ARCHITECTURE & DESIGN WWW . METARCHDESIGN . COM ISBN

978-0-615-45764-2

ALL RIGHTS RESERVED . NO PART OF THIS BOOK MAY BE REPRODUCED IN ANY FORM OR BY ANY MEANS , ELECTRONIC OR MECHANICAL , INCLUDING PHOTOCOPYING , RECORDING , OR BY ANY INFORMATION STORAGE AND RETRIEVAL SYSTEM , WITHOUT PERMISSION IN WRITING FROM THE PUBLISHER .

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( ECF :

ELEMENTAL CHLORINE FREE ).

EDITED BY MICHELE DIGIROLAMO COMMUNICATIONS MANAGER METCALFE ARCHITECTURE & DESIGN BO O K D ES I G N BY W W W . D E D EC U M M I N GS D ES I G N S . CO M

B RATT L E BO R O , VT

CONTENTS

Introduction

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Foreword

2 Paul W. Meyer The F. Otto Haas Director Morris Arboretum of the University of Pennsylvania

From the Architect

7 Alan Metcalfe, Principal Metcalfe Architecture & Design

The Job Was Play

17 Aaron Goldblatt, Partner Museum Services Metcalfe Architecture & Design

Project Team

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The entry through wooden hoop trellises gracefully transitions visitors from the ground to the sky.

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H E T R E E CA N O PY W A L K

at the Morris Arboretum of the University of Pennsylvania

INTRODUCTION

in Philadelphia combines the disciplines of architecture and exhibit design. It is both a structure and a huge exhibit. Although it uses interpretive panels, the real

exhibit consists of the surrounding trees, animals, sky, and the ground below.

The walkway begins at grade on the top of a hill, emerging through a trellis of oversized oak hoops. It meanders 450 feet through the urban forest, gently rising to five stories above the ground. It passes through a pavilion reminiscent of a Japanese teahouse, perched upon 20-foot stilts. A human-scaled bird’s nest dangles from giant metal chopsticks. A suspension bridge and huge netted hammocks beckon visitors onward.

The tree canopy walk is designed to be a fully accessible and sustainable structure. The long sloping sections were built off-site, trucked in, and hoisted into place by crane. The support towers are bolted to slender micropile foundations utilized as an alternative to larger conventional footings that could disrupt delicate tree roots. The steel is recyclable and virtually all the wood is locally sourced.

The attraction opened to public and critical acclaim in the summer of 2009 under the direction of Alan Metcalfe, Principal, and Aaron Goldblatt, Partner, at Metcalfe Architecture & Design.

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FOREWORD Out on a Limb: More Than the Sum of its Parts

M

ORRIS ARBORETUM’S TREE ADVENTURE EXHIBIT,

featuring the spectacular tree

canopy walk Out on a Limb, opened July 4, 2009, after more than five years of planning and development. Designed with Metcalfe Architecture & Design of

Philadelphia, Tree Adventure has exceeded our expectations.

The Arboretum-wide exhibit fosters dialogue among families about the importance of trees in our communities. It poses questions about why we need trees and, in turn, why trees need our help. It is fun, adventuresome, and exciting without being overly didactic.

Most importantly, it encourages visitors of all ages to experience and appreciate trees in new ways and share their observations with one another.

In Tree Adventure’s first 12 months, more than 128,000 visitors visited the Arboretum, up

30% over the previous year. And, they are indeed actively engaging with the exhibit and

also with one another, at a level beyond our greatest hopes.

As we live more and more in the cyber world, our busy lives and electronic devices often distance us from nature and one another. Real experiences in nature are increasingly rare. We know from surveys that the majority of our visitors come to the Arboretum in multi-generational groups and the primary reason they come is to spend quality time with family and friends in a beautiful, peaceful environment. Our Tree Adventure exhibit enhances that very personal experience, connecting our visitors not only with each other, but also with trees and the natural world, encouraging them to see what’s really around them.

So I invite you to use Out on a Limb, the canopy walk feature of the Tree Adventure exhibit, as an opportunity to engage family and friends with the Arboretum, allowing

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them to experience a small part of an urban forest canopy. And, be sure to visit all of the Tree Adventure stations throughout the Arboretum. With deepened appreciation and renewed powers of observation, I hope we will all be more attuned to the needs of trees and inspired to better tend the urban forest in which we live.

We feel fortunate to have partnered with the imaginative minds at Metcalfe Architecture & Design in the development of this fully accessible and sustainably designed exhibit. It is both wildly popular and award winning.

Walking in the treetops is a glorious experience. I invite you to give it a try in the Morris Arboretum’s urban forest canopy on Out on a Limb.

. — Paul

W. Meyer The F. Otto Haas Director Morris Arboretum of the University of Pennsylvania

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VIEWS VIEWS

STRUCTURE AND NETTING

form two“wading pools in the sky”at 50 feet into the tree canopy for gathering and playing

Arms of structure work with trees to create an outdoor room

BIRD’S NEST

of woven sticks hanging from a cable provides a hidden spot for escape

PAVILION

perched on 20-foot legs features transparent screen walls that provide a sense of enclosure and frame views

CHESTNUT OAK SUSPENSION BRIDGE

Zigzag of path emulates Chinese garden design and offers a slow journey with a new vista at every turn

Site Plan

ENTRY TRELLIS

provides a moment of compression, tension and transition

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H E T R E E CA N O PY W A L K

brought together worlds within the wood—and within

our practice. Members of the architecture and exhibit teams collaborated on

FROM THE ARCHITECT

this project and worked alongside fabricators, construction crews, Arboretum

educators, funders, and end-users in a way that yielded significant results.

Out on a Limb is a literal and metaphoric bridge suspended between the earth and sky.

It marks the juncture between these two places and makes each accessible to the other.

Like an open-air theater, the canopy walk blends nature, artifice, and experience. It spans the divide that separates people from trees and shows them the forest from the vantage point of the animals that live there.

The entrance at the top of the hill creates a moment of transition. Repeating hoops mark the entrance as the first of several transitions defined with circular portals echoing Chinese moon gates. The ground gradually drops away, transforming visitors’ sense of place, and opening views to the treetops and sky. From the entrance on flat ground at the top of a slope, visitors move deeper into the forest along the informal asymmetrical boardwalk path.

The ultimate design was organic in its evolution. The footprint of the structure was revised in the field to accommodate the unpredictable location of tree roots. Software used by our structural engineers allowed us to envision and design an elevated path that did not depend on conventional bridge design. We pursued the feeling of a tree house, perched upon the rugged steel structure found in park rangers’ smoke towers.

The pavilion, a midway point on the journey, is for gathering, shelter from the weather, and a gateway to unexplored areas beyond. This open-air building, sitting on 20-foot steel 7

legs, takes its form from traditional Japanese tea houses and substantial wood detailing that is reminiscent of 19th century Great Camps of the Adirondacks.

Our interest in biophilia, the innate love human beings have for the natural world, inspired us to use natural details throughout. The bird’s nest, for example, employs literal devices like three oversized blue eggs, as well as more abstract natural components like sticks, vines, and wires to create a sense of enclosure. Larger features like a suspension bridge comprised of whale bone-like ribs lead to this secret hiding place hanging high above the ground that provides a sense of enclosure for visitors looking down at the world below.

Transitions from solid to semi-solid to almost transparent materials occur throughout the tree canopy walk, toying with visitors’ senses of adventure and risk. The wooden boardwalk is solid but its transformation to metal grating and ultimately to netting dares visitors to proceed. A virtually transparent mesh of stainless steel “Invisinet” spans the end of every walkway, and play areas create pools of rope netting suspended 50 feet above the ground.

Both can cause nail-biting tension for parents and hesitancy in some children but ultimately create a feeling of excitement.

As architects and designers we are often so focused on putting what we know into the spaces we design that we are sometimes surprised to discover how much they can teach us. The tree canopy walk project challenged our office to move beyond the learned and the expected. And the lessons it yielded have been, like the forest itself, inspiring, humbling, and unpredictable.

—Alan

Metcalfe, AIA, LEED AP Principal Metcalfe Architecture & Design

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Concept Rendering 9

North Elevation

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West Elevation

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Bird’s Nest Section View

Conceptual models of the bird’s nest.

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Construction.

The bird’s nest and suspension bridge await a trip on the crane.

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No instruction required.

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W

E P L AY , W E L E A R N .

We learn about the realm in which we are playing, we

learn about our fellow players, and we learn about our playthings.

THE JOB WAS PLAY

When we play with something, we learn to value it.

This principle inspired and informed our design for Tree Adventure. Set in five different locations across the 92 acres of the Morris Arboretum of the University of Pennsylvania, this new exhibition was organized around tree-focused activities with the purpose of encouraging families to play together. The centerpiece is Out on a Limb, a tree canopy walk.

It is a fool’s errand to define play too tightly, but I believe there are some characteristics common to play in all its forms. In designing the canopy walk we carefully examined each of these characteristics.

FA M I L I A R I T Y A N D N O V E LT Y

To make us comfortable enough to relax our inhibitions and really play, the environment must be sufficiently familiar to feel safe. Important elements are recognizable; we understand how the space works. But there is enough novelty to draw us in. Something is new here and enticing us to explore.

We can hardly open our eyes outdoors without seeing a tree. This is as true in many urban places as it is in suburban and rural settings. Even if they never penetrate our consciousness, trees are there and we are, in some way, familiar with them. The tree canopy walk confronts us with trees in ways we almost never get a chance to experience.

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RISK

The invitation to play is most compelling when we have some sense of risk, maybe even danger. Without risk, there is no challenge. The danger does not have to be real; in fact when the perceived risk is too great, there is no play. We all have our own tolerance for risk—a rock climber’s threshold for physical risk may be higher than a gardener’s, but both need a challenge to enter into play.

Looking down through open steel grating as you walk five stories above the forest floor has an intrinsic sense of risk for many. Ramp it up by stepping off the grate onto a soft rope net 50 feet up, and the risk pool deepens. Balcony railings virtually disappear—leaving the feeling that nothing stands between you and a flight into the treetops.

O P E N - E N D E D N ESS

Play depends on the possibility of many potential outcomes. Without those imaginative possibilities, play becomes something more like work.

There are no instructions about how to engage here. The nest suggests activities by its very design, but there are as many ways to play with it as you can imagine. The kinds of play engendered by the net climb could not be more open-ended.

SO C I A L E N GAG E M E N T

Solitary play can be richly rewarding. We experience it all the time. But with each new participant, the rewards of play multiply. We have all experienced the joy of sharing a playful afternoon with a loved one—learning how they engage in play and expanding our definitions to encompass theirs.

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What we had not anticipated was the social interaction the net climb would invite. We were focused on the perception of risk. But people sit on the edge, dangling their feet into it like a wading pool, watch one another’s children, laugh and talk. Certainly family groups share their joy in the experience, but the happy surprise for the design team was the sight of strangers crossing social barriers to play together, expanding the meaning of the phrase “social climbing.”

TIME

We need enough time to play. It takes time to arrive at an emotional place; some call it “flow,” where we are fully engaged, maybe even lost in our play. We need the time and authority to determine when the play starts and when it stops. We need the time in a single play experience and we need to set aside time to play on a regular basis. We can get better at play, but it takes practice, and practice takes time.

Out on a Limb meanders through the forest, switching back and forth, providing space at each turn to stop and listen, smell, and see the forest environment as if for the first time.

Binoculars, listening stations, and graphic panels give learners of all kinds reasons to stop, dig deeper, and savor their journeys. Each switchback, each feature, acts as a speed bump, slowing down the experience. Visitors experience deep sensory pleasure being among the trees, and they return to “practice” this play.

— Aaron

Goldblatt Partner Metcalfe Architecture & Design

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Entry trellis.

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Overleaf: The ancient chestnut oak always dominates the design.

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Visitors must yield the path to the chestnut oak.

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Dappled sunlight inside the bird’s nest.

Suspension bridge leading to the bird’s nest.

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Opposite: Woodwork in the pavilion.

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The pavilion’s roof opens to the sky at dusk.

Wood and steel join to create the pavilion’s branch-like legs.

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Tulip trees rise from the netting.

Opposite: Steel and leaves in the forest.

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Transparent walkways perch on steel structure five stories above the forest floor.

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P R OJ ECT T EA M

Architecture & Exhibit Designers/ Metcalfe Architecture & Design Alan Metcalfe, AIA, LEED AP Aaron Goldblatt Paul Trapido Jason Manning Matthew Pickering Chris Kircher, AIA Structural Engineer/CVM Engineering Civil Engineer/Hunt Engineering Company MEP Engineer/Marvin Waxman Consulting Engineers Custom Wood Fabrication/Stauffer Woodworking for FYT, Inc. Exhibit Fabricator/Sparks Exhibits and Environments Construction Manager/CVM Construction Lighting Designer/Grenald Waldron Associates Morris Arboretum Staff Design and Construction Management/University of Pennsylvania Facilities and Real Estate Services All architectural drawings

by Metcalfe Architecture & Design All photographs by Paul Warchol except the following: Guillermo Torres: pp. vi, 26 Metcalfe Architecture & Design: p. 13 Laurie Beck Peterson: pp. 14–15, 33, back cover Paul W. Meyer: pp. 16, all three photos; 18 Shawn Evans: p. 19

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